feat(03-02): implement animation library — 7 types with registry and factory

- AnimationBase ABC with render(t, led_count) and from_params() contract
- SolidColorAnimation: time-independent uniform fill
- ChaseAnimation: moving lit segment with forward/reverse support
- PulseAnimation: sine-wave breathing effect (speed maps to period)
- RainbowAnimation: HSV hue cycle across strip via colorsys.hsv_to_rgb
- StrobeAnimation: on/off flashing at 1-20 Hz with configurable duty cycle
- ColorWipeAnimation: progressive fill from start or end
- FireAnimation: Fire2012 algorithm with cooling/sparking/heat-to-color mapping
- ANIMATION_REGISTRY + create_animation() factory function
- All 24 tests passing

lightsync/animations/base.py

@@ -0,0 +1,28 @@
+"""AnimationBase ABC — all animations implement render() and from_params()."""
+from abc import ABC, abstractmethod
+
+
+class AnimationBase(ABC):
+    """Pure animation renderer — no I/O, stateless or state-per-instance.
+
+    Each animation computes pixel data from time t and strip length.
+    No networking, no disk I/O — just math.
+    """
+
+    @abstractmethod
+    def render(self, t: float, led_count: int) -> list[tuple]:
+        """Render frame at time t (seconds since animation started).
+
+        Returns list of (R, G, B) tuples, length == led_count.
+        All channel values in range 0-255.
+        """
+        ...
+
+    @classmethod
+    @abstractmethod
+    def from_params(cls, params: dict) -> "AnimationBase":
+        """Construct from CueModel.params dict.
+
+        Missing keys use animation-specific defaults.
+        """
+        ...